The present invention relates to the transport of recipients under the action of jets of air, the recipients being supported and guided, when they are set in movement, via a protuberance on their necks. It applies more especially to the transfer in line of light recipients, in particular made of plastic, or again, of parisons for subsequently forming plastic recipients by stretching and blow moulding. The present invention more precisely relates to a device and to an air conveyor for recipients that are designed so as to limit the phenomenon of contamination and, in particular, of particulate and/or microbial contamination (bacterial, fungic, spores, micro-algae, etc.), of these recipients, during their transport, through the device.
The Applicant has already sought, in document WO 99/14143, to minimise the extent of contamination of the recipients by proposing an air conveyor the transport enclosure of which is completely closed, with the exception of the input and output openings for the recipients and which, furthermore, comprises means for plural controlled, unidirectional releases to the outside of the transport enclosure. Thus, the recipients transported inside the enclosure are completely isolated from the ambient air in which the conveyor is placed, which makes it possible to limit the phenomena of contamination in contact with this ambient air. The unidirectional controlled-flow releases of air enable the flow of induced air to be prevented from entering the transport enclosure, unlike a transport enclosure provided with free release, or exhaust, orifices, or again, a transport enclosure comprising two longitudinal side walls not closed in the lower portion. The unidirectional controlled-flow air releases also make it possible to regulate the pressure inside the enclosure to a level that is sufficiently low not to impair the conveyability of the recipients.
The transport enclosure described in document WO 99/14143 is tight, with the sole exception of its two end faces, which are open to allow the recipients to enter and to exit.
In the attempt to minimise contamination, the aforementioned document simply provides for sealingly connecting the air conveyor upstream and downstream, i.e. in the area of its two open end faces, to the other items of equipment constituting the complete conveying line.
This solution, which is not further described in the aforementioned document, is only conceivable, if it is to be efficient, if the items of equipment to which said input and output openings are themselves isolated from all contamination. In practice, this proves not to be the case.
The object of the present invention is to remedy this drawback and thus to provide an anti-contamination device that prevents polluted air from being induced into any installation in which recipients are transported.
It is sought to attain this object, of course, for application in an air conveyor the transport enclosure of which is completely closed, with air release means, as disclosed in document WO 99/14143. However this is not an exclusive application as it is also sought to attain this object for a conveyor the transport enclosure of which is provided with free-release orifices, or again, which has longitudinal side walls on either side of the recipient transport path, even although the efficiency of such conveyors in terms of non-contamination would be reduced. It is also sought to attain this object in order to prevent contamination at the input to machines, or again, when recipients pass from a given room to a room classified as having a low contamination level.
This object is fully attained by means of the device according to the invention. This is a device in which recipients comprising a protuberance in the area of their necks are moved along a transport path and in a direction T, the device including a transport enclosure which has a input face having an opening to admit the recipients; this enclosure contains:
a guide rail capable of supporting the recipients by their protuberances;
a longitudinal transport channel surmounting the guide rail.
Characteristically, according to the invention, the device comprises pneumatic means for blowing air in a direction G globally opposite to direction T, said means being capable of forming a frontal escape of air, from the inside towards the outside of the enclosure, via the admission opening of the input face.
This frontal air escape from the inside towards the outside of the enclosure opposes the ingress of the polluted ambient air in which the device is placed, via its entry opening.
Preferably, the pneumatic means for blowing air, in direction G, comprise a chamber for supplying pressurised air, the wall or walls of which, turned towards the recipient transport path, are pierced with orifices, in particular by slits, capable of forming jets of air orientated in direction G towards the admission opening of the input face.
If we consider direction T as being the longitudinal direction of movement of the recipients through the transport enclosure, the air jets have directions G which are all globally opposite to direction T, but which can have differing angular orientations; each air jet does not, therefore, necessarily have a direction that is diametrically opposed to direction T. The number of air jets and the angular orientation of each of them is determined in such a way as to create the sought after frontal escape, over the entire cross-section of the admission opening of the input face of the device.
In a first alternative embodiment, the transport enclosure comprises an upper compartment and a lower compartment, both of them being separated by the transport channel in the shape of an inverted U, and by two lateral partitions; in this case, the supply chamber of the pneumatic means is formed in or by the upper compartment, and the pneumatic means include, over the length L of the enclosure, a plurality of orifices, in particular slits, provided in the transport channel and, as applicable, the lateral partitions, and capable of forming air jets orientated in direction G, opposite to T, and inclined obliquely by an angle xcex1 in relation to the vertical.
As the orifices or slits are formed in the upper part of the lower compartment, it is necessary, on one hand, for the air jets formed to be inclined obliquely and, on the other hand, for these orifices or slits to be formed over a distance sufficient for all of the air jets, cumulatively, to be able to generate the sought after frontal air escape.
Distance L1 is, of course, a function of the height H of the admission opening of the input face. Preferably, L1 is in the order of 1 to 2 H.
In one preferred exemplary embodiment, L1 is in the order of 500 to 600 mm, xcex1 is greater than 30xc2x0, preferably 45xc2x0, and the speed of the air jets is between 7 and 13 m/s.
In a second alternative embodiment, the supply chamber of the pneumatic means surrounds the recipient transport path, at least above and on either side of said transport path and, preferably also, below it.
In the first alternative embodiment, the direction of the air jets is necessarily obliquely downwards as they originate from the upper part of the lower compartment of the enclosure. In the second alternative embodiment, the orientations of the air jets can differ as they can originate from all points on the periphery of the transport path.
Advantageously, the orifices are formed in the inner side walls and, also, preferably, in the inner lower wall, of the supply chamber. This arrangement, with orifices that are more homogeneously distributed over the inner walls of the supply chamber, makes it possible to reduce the length L2 of the enclosure, by comparison with the distance L1 of the first alternative embodiment. In this case, L2 would be rather in the order of H, or even smaller.
In order to improve further the efficiency of the device, orifices can also be provided in the frontal wall of the supply chamber, a frontal wall that serves as the input face of the enclosure. This particular arrangement makes it possible to create an area upstream of the admission opening of the input face, which prolongs the effect of the frontal escape, an area which proves particularly appropriate if there are no recipients in front of the device.
When the supply chamber according to the second variant completely surrounds the recipient transport path, preferably, the orifices are orientated in such a way as to form air jets the direction of which is precisely opposite to direction T.
On the other hand, when the supply chamber surrounds the recipient transport path solely above and on either side of it, preferably, certain orifices are orientated in such a way as to form jets of air that are inclined obliquely downwards.
When the orifices take the form of several levels of longitudinal rows, advantageously, the angular orientation of the orifices increases in proportion as the levels approach the bottom of the chamber.
The anti-contamination device according to the invention is implemented in combination with an air conveyor, or any other equipment that has exactly the same equipment as said device as regards transport of the recipients: a guide rail and, preferably, a longitudinal transport channel. The device can be implemented as a modular anti-contamination unit, added onto the input face of said equipment, and thus structurally independent thereof. Advantageously, the device is integrated into said equipment, in the upstream area thereof, with the input face of the equipment forming the input face of the device. The device thus serves as an anti-contamination input air lock for the equipment in question. This arrangement is all the more advantageous in the case of a conveyor or of equipment provided with pneumatic means for transporting recipients in direction T; the air supply to the conveyor or the equipment can, in fact, be used to supply the pneumatic means of the device.
In particular, in an implementation integrated in a conveyor according to the first alternative form of embodiment, see above, the air conveyor has a known structure, except that there is an input area in which the transport channel is not provided with slots orientated to form air jets in direction T, that is to say slits permitting normal movement of the recipients in said direction T. In this area are provided orifices, preferably slits, possibly similar to the traditional slits, but which are orientated to form jets in the direction opposite to T.